"One of my pet hates is people re-Tweeting praise, I loathe it more than anything else in the world," explains the 50-year-old, also known for his roles in Peter Mullan's 1998 black comedy Orphans, sci-fi series Primeval and the BBC period drama South Riding.

"It's like walking up to a stranger in the street and saying, 'So and so said that I was absolutely fantastic, did you know that?' You just wouldn't do that. You'd never in a million years do that, so why would you do it on Twitter?"

Loathe though he is tell the world of any praise he receives, he will use the platform to tell people about the new series of the BBC One show, which returns for a third run this month.

Based on the novels by Ann Cleeves - and also starring Alison O'Donnell, Steven Robertson and Julie Graham, alongside newcomers Ciaran Hinds, Archie Panjabi and Anna Chancellor - this series will see DI Jimmy Perez (Henshall) and his team investigating the strange case of a young man who disappears on a ferry crossing.

By Henshall's reckoning, it'll be "darker and a wee bit scarier" than the two previous outings, but what else should you know?

Although most of the action is set in the Shetlands, some of the scenes were filmed in Henshall's home town of Glasgow.

"There's something quite childish and exciting for me about filming in Glasgow," says the actor, who trained at the Scottish Youth Theatre before moving down to London, where he started his career on the stage.

"I'm not entirely sure what it is or if that sounds daft, but I like it. I get to revisit my youth and home town but in a completely different way, which is quite pleasurable."

One of the things he loves about the series is the number of new additions to the cast.

"As much as you like the people you work with every day, it's nice to have new people," says Henshall, who is married to Croatian playwright Tena Stivicic.

"There are some really good, young Scottish actors and it's always nice to have them come in - Sara Vickers, Jack Greenlees, Andrew Rothney - people like that, really terrific young actors. They bring good energy with them as well, because they're not some old 50-year-old."

As for dream co-stars, he has a few in mind.

"Obviously Peter Mullan is a good pal of mine. It would be nice to get Peter in to do something.

"Actually, I've always wanted to work with Archie Panjabi, so it's fantastic she's in this series. She was such an asset and liked by the whole crew."

But there is one person he hasn't yet snared.

"Obviously, if we could get Robert De Niro to come in, that would be lovely," he says with a laugh. "Why not? What else is he doing?"

As well as his role in Shetland, Henshall has also played an investigating officer in ITV crime drama Collision and BBC crime miniseries The Silence, and he's appeared in Lewis.

"Do you know, I didn't play a policeman up until I was 40, and then suddenly that's what I have been asked to play," he says.

"I suppose if the script and storyline is good, you've got to take what you're given, really. But I suppose I start to worry slightly that that's where I am going to end up, and that's the way people see me - hopefully not, but we'll see."

Despite all the grim crimes investigated in the series, it hasn't stopped fans from flocking to the Scottish archipelago.

"The hotel I stay in when I'm over there keeps saying, 'We had a group of Swedish people', and, 'We had a bunch of people from Canada who have come all the way to Shetland because of the series'," he reveals.

Over the years, the locals have taken to it as well.

"As with any community, they were a wee bit wary at the beginning, because they wanted to see if we would be a force for good or whether we were there to take advantage of the islands. They're fiercely proud Shetlanders, and rightly so," says Henshall.

"I feel like they wanted to be properly represented.

"It's taken a bit of time, but they see that we've always tried to be a force for good there; to tell good stories and make Shetland look like a place you'd really want to be."

To mark the end of filming the current series, the cast and crew had an unusual celebration this time round.

"We had a pirate party at the boat club, which I thought was going to be a nightmare, but it ended up being one of the best parties I have ever been to in my entire life," Henshall confesses with a laugh.

Afterwards, the troop went to the "one nightclub in Lerwick" where, again, they left their mark.

"Through the course of the evening, pirate gear was shed," says Henshall.

"Somebody left their jacket and went back the next day to an empty nightclub, and all they could see was this enormous pile of eye-patches and plastic swords, which did make me laugh."

Shetland returns to BBC One on Friday

Belfast Telegraph

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